Objective-c – Convert nsdictionary to nsdata

iphonensdatansdictionaryobjective cuiimagepickercontroller

have an app that can take a picture and then upload to a server. encoding it to base 64 and pass it thru a XMLRPC to my php server.

i want to take the NSDictionary info that is returned from UIImagePickerController delegate

-(void) imagePickerController:(UIImagePickerController *)imagePicker didFinishPickingMediaWithInfo:(NSDictionary *)info

and convert it to NSData so i can encode it.

so, how can i convert NSDictionary to an NSData?

Best Answer

You can use an NSKeyedArchiver to serialize your NSDictionary to an NSData object. Note that all the objects in the dictionary will have to be serializable (implement NSCoding at some point in their inheritance tree) in order for this to work.

Too lazy to go through my projects to lift code, so here is some from the Internet:

Encode

NSMutableData *data = [[NSMutableData alloc] init];
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
[archiver encodeObject:yourDictionary forKey:@"Some Key Value"];
[archiver finishEncoding];
[archiver release];
/** data is ready now, and you can use it **/
[data release];

Decode:

NSData *data = [[NSMutableData alloc] initWithContentsOfFile:[self dataFilePath]];
NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
NSDictionary *myDictionary = [[unarchiver decodeObjectForKey:@"Some Key Value"] retain];
[unarchiver finishDecoding];
[unarchiver release];
[data release];

Related Solutions

Ios – How to convert an NSString value to NSData

NSString* str = @"teststring";
NSData* data = [str dataUsingEncoding:NSUTF8StringEncoding];

Ios – Convert UTF-8 encoded NSData to NSString

If the data is not null-terminated, you should use -initWithData:encoding:

NSString* newStr = [[NSString alloc] initWithData:theData encoding:NSUTF8StringEncoding];

If the data is null-terminated, you should instead use -stringWithUTF8String: to avoid the extra \0 at the end.

NSString* newStr = [NSString stringWithUTF8String:[theData bytes]];

(Note that if the input is not properly UTF-8-encoded, you will get nil.)

Swift variant:

let newStr = String(data: data, encoding: .utf8)
// note that `newStr` is a `String?`, not a `String`.

If the data is null-terminated, you could go though the safe way which is remove the that null character, or the unsafe way similar to the Objective-C version above.

// safe way, provided data is \0-terminated
let newStr1 = String(data: data.subdata(in: 0 ..< data.count - 1), encoding: .utf8)
// unsafe way, provided data is \0-terminated
let newStr2 = data.withUnsafeBytes(String.init(utf8String:))

Best Answer

Related Solutions

Ios – How to convert an NSString value to NSData

Ios – Convert UTF-8 encoded NSData to NSString

Swift variant:

Related Topic